Electron optical instrument and camera therefor



Oct.4,1949. I.B.BENSEIN I 2,483,872

ELECTRON OPTICAL INSTRUMENT AND CAMERA THEREFOR Filed Nov. 10, 1945 I 2sheets-sheet 1 I I I Invehtor: 13cm B. Bensen,

His Attorney.

I. B. BENSEN ELECTRON OPTICAL INSTRUMENT AND CAMERA THEREFOR Filed Nov;10, 1945' 2 Sheets-Sheet 2 Inventor: Igor B. Bensen, bgMfiM His-Attorney.

Fig.4. 42

Patented Oct. 4, 1949 UNITED STATES .OFElC-"E ELECTRON OPTICALINSTRUMENT AND CAMERA THEREFOR I Igor B. Bensen, Schenectady; N2Y.,'assignor to General Electric Company, a corporation of New YorkApplication November 10, 1945,.Serial N0. 6227.953

"12 Claims.

My invention. relates to apparatus for examining objects with the .aidofelectron beams, and

particularly to cameras used in such apparatus.

In electron optical instruments, such as electron microscopes andelectron diffraction instruments, it is customary to produce an enlargedimage or a pattern, as the case may be, of an :object being examinedjbycausing a beam of high .speed electrons to fallupon that object and,after transmission therethrough or reflection therefrom, to fall upon afluorescent screen. It is desirable to record the images thus producedon a photographic plate forpermanent record purposes. It is known thatgreater speed in photographing the images is obtained if the recordingis done within the evacuated instrument and by intercepting theelectronic beam on a photographic plate positioned intermediate theobject being examined-and the fluorescent screen. Since .the completestructuremust be .hig hlyevacuated,

It is a furtherobject of my invention to provide a camera in anevacuated structure. and means .externalto the evacuated region. forsequentially placing a photographicplate into a recording positionandremoving it ,from that position.

It is still another object of my invention to provide a new and improvedstorage chamber for photographicplates. I I

It is a still further object of my invention to provide a new andimproved magazine or supply. .chamber for a camera inwhich photographicplates stored therein are ejectedsingly andthe remainingplates in thechamber are removed sequentially to an ejecting position.

-It is still another objectof my inventionto proh vide a new andimproved-electron optical instrument provided with both a. fluorescentviewing screen and means intermediate the screen and an object beingexamined for photographing the electron images or patterns produced.

Briefly stated, in one form of my invention a camera is providedwithinan electron diffraction instrument and consists of a magazinesupported above the optical axis of the instrument andprovided .withanexternal control for ejecting photographic plates into a plane normal tothe optical axis and additional external 'means for removing the platesfrom such position and positioning the plates, after exposure, in astorage chamberlocated below the optical axis.

A feature characterizing the inventionis the maintaining of photographicplates in a plane normal 'to the -optical axis of the instrument andallowing the plates to fall by gravity in successive steps from themagazine 'to an exposure position .and ultimately to a storage chamber.

. 'Ihefeatures of my invention which I believed to be novelgarewsetforthwith particularity. in the appendedclaims. My invention itself, however,both as -to its organization and method of operation, together withfurther objects and ad- .vantages thereof may best be understood by ref-..erence to. the. following description taken in connection with,thenaccompanying. drawings in "which Fig. 1 is a'front-elevation .Viewof .an electron difiraction instrument including the camera of myinvention; Figs. 2 and 3 are side and front .views, partly incross-section, of a cameraem- .ployed in the instrumentof Fig. 1; Fig. 4is a side elevation view, partly in section..of the magazineorsupplychamber employed in the camera of Fig. 2; Fig. 5 is a section view alongthe lines 5-5 of Fig. 4-, and Fig. 6 illustrates the mechanismof Fig. 5in an operated condition; Fig. Tis a bottom .view of the magazine ofFig. 4; Fig. 8 is. a side view, partly in section, of'the photographic.plate storage chamber employed in the cameraof Fig- 2; Figs. 9 and 10.respectively, illustrate an operating mechanism of the storage chamberof Fig. 8 in closed and .open position;

and Fig. is a section view of Fig. 9 taken along thelinel I-l I.

Referring to Fig. 1, Ihave there shown an electron diffractioninstrument which includes an operating panel l-loehindv which isdisposed an electrongun or. filamentary source of electrons. .electronsemitted from the gun are focussed by The meansbf, a focussingyoke 2. tobe reflected from anobject to be examined and supported upon a suitablespecimen support 3. The specimen sup- ..port 3 is contained within aspecimen chamber 4 and its position may be. adjusted by means of a.manipulator- 5 through three mutually perpendicular directions, aswellas two axesof rotation.

Amanipulatorof this type is describedin my application, Serial N 0.562.7 ,952, now .Patent 2,440,067,

filed concurrently herewith.

.The electron beam, after reflection from the specimen being examined,isallowed to fall upon a fiuorescentscreen 6 supported at the endof acontainer 1. The electron beam, when it falls upon the fluorescentscreen 6, forms a diifraction pattern thereon. In order that the patternthus formed may be permanently recorded, a camera 8 is provided, theconstruction of which is pointed out in greater detail hereinafter.Means are provided for intercepting the electron beam while thephotographic plate is being lowered into a plane perpendicular to theoptical axis of the diffraction instrument. This means comprises ashutter 9, externally manipulated by a control handle 10, which may bemoved into and out of the path of the electron beam. The entireinstrument including the specimen chamber 4 and the camera 8 may behighly evacuated by any suitable means, such as a vacuum pump (notshown) and which may be connected to the instrument through a tubulationl l.

Referring now to Figs. 2 and 3 jointly, I have there shown the camera ofmy invention as comprising a vertical rectangular container 12 whichconnects with the container 1 and which extends in a directionperpendicular to the axis of the electron beam indicated by the arrowl3. The camera 8 comprises a magazine or supply chamber Hi, a storagechamber l5, and a plate supporting mechanism .15 arranged intermediatethe members i4, i5. The members I l-l6 are supported from a verticalframe member ll which is arranged to slide in a supporting channel orslide is. Rigidly attached to the vertical member 2, as by means of thesupporting bracket 59, is a top or closure member 29. The closure member28 is arranged to fit in a shoulder 21 at the upper end of the verticalcontainer l2 and is sealed by means of a rubber gasket 22 and a flange23 bolted to a cooperating flange 24 at the upper end of the container[2. The cover preferably is provided with a handle 25 by means of whichthe members 14-; may be withdrawn as a unit from the container l2,

The magazine I4 is provided near the lower edge of its sides with a pairof screws 26 which are adapted to fit into a hangar 2'! attached to thesupport ll. At its upper end, the magazine i4 is retained in a verticalposition by means of a spring clip 21" adapted to engage the outer edgeof the magazine. Similarly, the storage chamber 55 is adapted to besupported at its lower end by a pair of hangars 28 and, at its upperend, by a pair of pring clips. The photographic plates contained withinthe magazine Iil may be ejected singly by means of an externallyaccessible push button control 30 which actuates an operating rod 3|attached to the lower end of the magazine I4. After being ejected fromthe magazine M in a manner to be described later, a photographic plate32 is allowed to fall by gravity to a position perpendicular to theelectron beam 53. It is retained in this position by means of a pair ofguides 33 and a plurality of springs 34 which engage the front surfaceof the side rails 35 of a frame or holder which surrounds thephotographic plate 32. The holder is provided at its lower edge with apair of pins 36 which rest upon movable supports 31. The photographicplate is centered by means of a pair of springs 38 which engage the sideedges of the rails 35. The storage chamber [5 is likewise provided withan operator 39 for moving the supports 3? to lower the plate 32, afterexposure, into the storage chamber I5 in a manner described hereinaiter.External means are provided for actuating the operator 39 and comprisesa push button 40 supported on the frame l2 and mechanically linked withthe operator 39 through a vacuum-tight seal 4|.

The magazine or photographic plate supply chamber M is shown incross-section in Fig. 4 and comprises a rectangular metallic box 42having a inclined bottom 43 and a light-tight side Wall it having acentral aperture. The side wall 44 supports a pair of spaced channelmembers 35, 45 and a light impervious wall 4'! supported on the channel46 is spaced from Wall 44 so that light passing through the centralaperture in wall 44 cannot reach the interior of the magazine. Thecentral aperture preferably is sufficiently large that the magazine maybe evacuated rapidly when it is positioned in an electron diffractioninstrument. The wall 41 prevents light from reaching the plates 32 whenthe magazine is removed from the instrument. The magazine Hi is adaptedto receive a plurality of photographic plates 32 and is provided with apair of fiat springs 48 which engage the side rails 35 of the plateholders to maintain the plates and their associated holders pressedagainst the right-hand wall 49 of the magazine.

The inclined bottom of the magazine i provided with an operatingmechanism which comprises a plurality of superposed members comprising achannel 56 movable by operating rod 3!, a retainer plate 5!, a movableplate member 52, a closure member 53, a plate restraining member 54, andan additional retainer 55.

The relation of the operating members for ejecting a photographic platefrom the magazine M is best understood by reference to Figs. 5-7,inclusive, in which Fig. 5 shows the mechanism with the closure member53 in its closed position and Fig. 6 shows the closure member 53 in itsopen position. Fig. '7 shows a bottom view of the operating mechanism.In the operating mechanism, the operating rod 3| is affixed to thechannel member 5:: which is provided with a pair or" tongues 56, 51which fit into the slotted retainer plates 51 fastened by means ofscrews 58 to the bottom wall 43. The channel is biased toward theright-hand position, as seen in Fig. '7, by means of a spring 59 whichis attached between a stiffener 60 at the left-hand end of the channel50 and a stud 6| attached to the righthand retainer plate 5|. Alsoattached to the channel 50 is a thumb operator 62 by means of which theclosure member 53 may be operated when the magazine is being filled withphotographic plates. The channel 50 is likewise provided with anaperture adapted to receive a pin 63 which is affixed to the movableplate member 52 and which passes through a slot 64 in a retainer plate65 attached to the bottom wall 43 and interposed between the channelmember 50 and the movable plate 52. The movable plate 52, in turn, isprovided with a pair of parallel slots 68 inclined at an angle to thedirection of motion of the channel 50 and the movable plate 52. Theslots 66 are adapted to receive pins 51 attached to the closure member53. Thus it is seen that, when the operating rod 3! is moved to the leftto move the channel 50 and the pin 63, the movable plate 52 i likewisemoved to the left and the slots 66 engaging the pins 51 move the closuremember to its open position seen in Fig. 6.

The movable plate 52 likewise is provided with an aperture to receive apin 68 which is attached to the plate restraining member 54 and passesthrough a slot 59 in the bottom wall 43. The plate restraining member 54is limited to transverse were motions mtains of l the retainer 55- whichis screwed to the esteem-wan '43 and which is "provided with alongitudinal slot in to receivethe plate restra ining memb'ei' i l.JZiikewisef-the closure member-53 is provided wi-th a n'otch 1 I whichis iadapt'edto receivethe pin-6E during the operation of the closuremember; and "the plate restraining mem ber randwhich functions as a stopto limit -the motion of the operating 'mechanism zin the lef and:direction. l The .plate restraining member. kat'i s'- two ends isprovided with :upturnediedgesillwhich arefiaidaptedito.passbehind thepins-36 of theisecondtplate zin thenma'gazine :to: move the '-'sec'ond.-and. .:all other Iiplates to theiback 10f: the magazine .releasing.ressure on .thmplataa'da' acent thewallifl.

rxxI-n .-:-the nompletez'ioperation Joli i the :magazinezoperatingvrenechanism :to eject a. :photog-raphic plategztherzoperating.rod .Bi by movement of the channel 50 to the left moves the spinZ63-ion the :mdvable: plate :52. Theslots-rfifi in the plate '52 engage:pins -6:'l ion the closure memberi53tomove :thisclosuremembertotherear, thus leaving the plateholder adjacent wall 'unsupportedagainstyerticalrmovement. At the same time, the pin 168;, which fits :into themember Hand is attached to.the platefrestraining-member '54, moves theiupeturnededges J2 to-engage the pins 36 at the :bottom lot the secondplate holder and to move this .platecand the remaining ,plates to therear :oi .theiimagazine, releasing the lateral pressure -onthe firstplate-:ofthe magazine. As a consequence, the firstplatein the magazineis-no longer supported and .drops free y-through the opening .inth'e.bottomof'themagazine into the guides 33 at the positionshown in.Fig 3.-When.pressure on thetoperating rod 3| is released, the spring 59.causes the channel 50 to return to its normal position 'and'thelclosuremember '53-.to close the op'eningin the bottom Wall '43. "At the sametime, 'theup-turn'ed "edges "12 'are moved tothe right,

releasingthepins tfi on the next plate of the magazine. The'flatsprings48 press the remaining plates to the" right, causing the :last plate to"be plac'ed *in an -ej ecting position.

l he 'storage chamber lS for exposed plates'is -shown in-"crosssectional view in Fig. 8 and is-sim- 'ilar' in construction to the-magazine 4-4; with the exception that ttheoperatin'g mechanism is atthe Jtop of'th'e chamberand both-the top and bottom 'wallsarefin ahorizonal position." The light-tight construction of -theleftwall issimilar to that of .ithezzma'gazine rlA a-nd similar elements areidentibyzsimilar. reference numerals differentiated lbyepriming.fllhe'st'onage ioh'amber 15 is likewise provided a flat :spring :48 forplacing" the platesmgainstuthe leftehand wall 13 ofthe 'storragechamber. "Dhe"operatingmechanism for the closure member 14 is similar tothat employed-in econn'ectionwit'h the magazine,"with the excep---tion-: that. the; plate restraining member. '54 andits:operatingmechanisms are not required. An-

" other additional feature of the. closure operating .imeohanism' of thestorage chamber: is the sup- .ports :3:|' which 'are attached-to thec'losure mem- -berr-1l4iandiarecnoved to the left, as seen in Fig.8.-1when thechannel' 5.0 is moved. tothe rearito open :the.storagewchamber to permit a::photographic.plateito fall" into thestorage chamber.

-.-Since the: plates in :rthe storage chamber iare' apressedatowardtheright n/all J3 by the IIflEti springs :48; .Itprovide means connectedwith. the

aciosureioperating mechanism to-move: the plates within the --chamber 1:to the -:rear ':to. :permit the "entrance [of amew plate. Thiswmeansccomprises ,6 a-'-tcg"g-le"mechainismconsisting of afileverFlipivoted about astud 16 in the-side wallof 'thetstorage chamber. M Atits upper end,- theievor 15- is provided with a'tongue' llwhichfit'sinto aigroove in the cl'osureapl'ate J4.ifnttermediatertheitongue andthe pivot 16,;the lever lihas-iattached toit a slide 18 which; fits into .:a groove 19..in. the side wall 1of.thezstorage 'acham'ber. The .S1id6:."|.8 is formed of: a .spring:material.:ahdzis-apmvided atlits right-hand. end with .a hook which-usadapted to slide overthe inclined surface .ofi-a notch 8| provided inthelsideira-il :35 of the whotograp'hic plate holder. A similarslide {J8:and groove '519 are provided at the lower endcfathe magazine to:engagela second-notch Bl on :the siderail35. The-lower slides'l8: isoperated by a lever ilg pivoted about a stud $3.:a-ndwhich has -asocket-ti l for receiving a :ball joint 1851813 the lowerzend of thelever 15. In the operationuof the mechanism for opening. the storage Ichamber ..i-5 to. permit;- entrance orzremo-valpf a photographic plate,when the operating. rod. 1.39 is pressed, the channel :50 through theassociated mechanism moves the closure member 314 to the left, as seenin Figs. 8 -11., thus formingan opening through which aiplate ,may enterthe storage chamber. At the same time,..the.lever 1:5.is moved to theleft, causingthe.slidelil'a andthe hooktll, which engageswanotch.8.l,.to.move the plates present in the storage chamber. to. therearagainst the pressure of spring'48'. "When the pressure on the operating.rod 39. is removed, the spring .59 causes the channel ';50.' to movertoithe front in the views shown and the closure member 14120 close thestoragechamber. At the same time, the slides .18 move to theright,..causingi the flexible ho'oktfl to. slide over the inclinedsurface .of'the notch 81 of theiplate adjacent wall "Band to engage thatnotch preparatory to moving this pl'ate't'o the rearupon next operationof the'closure mechanism.

"Animportant advantage of my new and improved camera isJthat it iseasily inserted .and withdrawn from a region to beevacuatedJFurthermore, the magazineand storage 'chamber arecial'hand'ling.

- Since the photographic plates are allowed to proceed by gravity"fromthe magazine to-exposure position and, subsequently, to storagechamber, the "external operatingmechanism for the camera is relativelysimple and requires" no "extensive sealing or elaborate manipulators.

Operation of the improvedelectron diffraction instrument incorporatingmy improved camera is facilitated by including the shutter s'to-cu'thfithe electron beam when a desired patt'ern or immy invention, it will ofcourse-be understood that I do not wish to be limited theretosincewar'ious .zmodi fications may be made, and I- contemplate *bythe:appended claims lto cover. anysuch m'odi- ;.fications :asxfall" Withinthe true spirit and: scope ofxmyinvention. I I

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1, In a camera for use in an evacuated region and having an optical axisarranged in a substantially horizontal position, a container adapted tobe evacuated, a photographic plate supply chamber supported within saidcontainer in a position above said axis and a plate storage chamberpositioned within said container below said axis, each of said chambershaving closure means therein and being arranged to hold a plurality ofphotographic plates therein, each of said cham bers having a pluralityof imperforate walls and a perforate wall to provide substantially freecirculation of air between said container and the chamber to facilitateevacuation thereof, means for operating the closure means of saidsup-ply chamber to release a plate from said supply chamber to fall bgravity to a position normal to said axis, means including meansconnected with the closure means of said storage chamber supporting saidplate in said normal position, and means including means for operatingthe closure members of said storage chamber for releasing said platefrom said normal position.

2. In a camera for use in an evacuated region and having an optical axisarranged in a substantially horizontal position, a container adapted tobe evacuated, a photographic plate supply chamber supported Within saidcontainer in a position above said axis, means ejecting a first platefrom said chamber to fall by gravity to a position substantially normalto said axis and for moving a second plate to an ejecting position,means including a storage chamber positioned within said container belowsaid axis for supporting said first plate in said normal position, andmeans releasing said first plate from said normal position to fall bygravity into said storage chamber, each f said chambers beingconstructed and arranged to provide free circulation of air between saidcontainer and the chamber to facilitate evacuation thereof.

3. In a camera for use in an evacuated region and having an optical axisarranged in a substantially horizontal position, a container adapted tobe evacuated, a vertical supporting means arranged within saidcontainer, a photographic plate supply chamber supported by saidvertical means in a position above said axis, a plate storage chambersupported by said vertical means in a position below said axis, meansfor transferring a plate by gravity from said supply chamber to aposition normal to said axis, and additional means for transferring saidplate by gravity from said normal position to said storage chamber, eachof said chambers being constructed and arranged to provide freecirculation of air between said container and the chamber to facilitateevacuation thereof.

4. In an electron optical instrument of the type having an evacuatedchamber having an axis along which a beam of electrons is projected, acamera arranged to be removably positioned in said chamber, said cameracomprising a photographic plate supply chamber supported above said axisand a storage chamber positioned below said axis, means external to saidevacuated chamber for transferring a plate from said supply chamber to aposition normal to said axis, and additional means external to saidevacuated chamber for transferring said plate from said normal positionto said storage chamber, said supply and storage chambers each beingconstructed and arranged to provide free circulation of air between theregion therewithin and said evacuated chamber.

5. In an electron optical instrument of the type having an evacuatedchamber having an axis along which a beam of electrons is projected, aviewing screen supported at one end of said chamber, a camera positionedin said chamber adjacent said viewing screen, said camera comprisingmeans supporting a photographic plate above said axis, means external tosaid chamber for transferring said plate from said position to aposition normal to said axis and in front of said screen, and additionalmeans external to said chamber for transferring said plate from saidnormal position to a position below said axis, said camera beingconstructed and arranged to provide substantially free circulation ofair between said chamber and a photographic plate for all positions ofthe latter.

6. In an electron optical instrument including an evacuated chamberhaving an axis along which a beam of electrons is projected, a viewingscreen supported at one end of said chamber, a camera positioned in saidchamber adjacent said viewing screen, said camera comprising meanssupporting a photographic plate above said axis, means external to saidchamber for transferring said plate from said position to a positionnormal to said axis and in front of said screen, additional meansexternal to said chamber for transferring said plate from said normalposition to a position below said axis, and means for intercepting saidbeam of electrons, whereby said beam may be interrupted while said plateis being transferred between said positions said camera beingconstructed and arranged to provide substantially free circulation ofair between said chamber and a photographic plate for all positions ofthe latter.

7. A discharging container for photographic plates comprising anenclosing structure adapted to be evacuated and comprising a pluralityof imperforate walls and a perforate wall, an imperforate member inspaced relation with said perforate wall and forming a light-tight sealtherewith, said structure having an inclined bottom wall having anaperture at its lowest point, resilient means for moving a photographicplate in said container down said inclined wall toward said 'saidcontainer falls by gravity through said aperture.

8. A discharging container for photographic plates of the type having arectangular supporting frame and a pin on an edge of said frame compriseing an enclosing structure adapted to be evacuated and comprising aplurality of imperforate walls and a perforate wall, an imperforatemember in spaced relation with said perforate wall and forming alight-tight seal therewith, said structure having an inclined bottomwall having an aperture at its lowest point, said plates being arrangedvertically in parallel relation in said container with said pinsadjacent said inclined wall, said bottom wall including a movableclosure member for said aperture, an operating mechanism for saidclosure member comprising a member movably supported on said bottomwall, means connected with said member and operated thereby for engagingthe pin of the second lowest plate in said container, and meansconnecting said movably supported member and said closure member formoving said closure member to uncover said aperture, whereby the lowestplate onl in said container falls by gravity through said aperture.

9. A discharging container for photographic plates having a rectangularsupporting frame and a pin on an edge of said frame comprising an emclosing structure adapted to be evacuated and comprising a plurality ofimperforate walls and a perforate wall, an imperforate member in spacedrelation with said perforate wall and forming a light-tight sea-ltherewith, said structure having an inclined bottom wall having anaperture at its lowest point, resilient means within said structure formoving a plurality of plates within said container to the lowest pointof said inclined wall, said plates being arranged vertically in parallelrelation in said container with said pins adjacent said inclined wall,said bottom wall including a movable closure member for said aperture,an operating mechanism for said closure member comprising a membermovably supported on said bottom wall, means connected with said lastmember and operated thereby for engaging the pin of the second lowestplate in said container, and means connecting said last member and saidclosure member for moving said closure member to uncover said aperture,whereby the lowest plate in said container falls by gravity through saidaperture.

10. A storage chamber for plate-like articles comprising an enclosingstructure adapted to be evacuated comprising a plurality of imperforatesides and a perforate side, an imperforate member in spaced relationwith said perforate side to form a light-tight seal therewith, saidstructure having a wall having an aperture therein, a closure member forsaid aperture, operating means for moving said closure member to uncoversaid aperture, means normally biasing a plate-like article within saidchamber into alignment with said aperture, and means operated by saidoperating means for moving said article out of alignment with asidaperture whereby an additional article may be introduced into saidchamber.

11. A storage chamber for photographic plates of the type having arectangular supporting frame and including a notch at the outer edge ofsaid frame comprising an enclosing structure adapted to be evacuatedcomprising a plurality of imperforate sides and a perforate side, animperforate member in spaced relation with said perforate side to form alight-tight seal therewith, said structure having a top wall having anaperture therein, a closure member for said aperture, operating meanscarried by said top wall for moving said closure member to uncover saidaperture, resilient means within said chamber for moving a photographicplate therein in alignment with said aperture, and means operated bysaid operating means and including a finger linked to said operatingmeans and movable therewith, said finger being positioned to engage saidnotch on said plate and upon movement of said operating means to movesaid plate out of alignment with said aperture, whereby an additionalphotographic plate may be introduced into said chamber.

12. A storage chamber for photographic plates of the type having arectangular supporting frame and a notch on said frame comprising alighttight enclosure adapted to be evacuated and comprising a pluralityof imperforate sides and a perforate side, an imperforate member inspaced relation with said perforate side to form a, lighttight sealtherewith, said enclosure having an end wall having an aperture therein,a closure member normally biased to cover said aperture, operating meansfor moving said closure member to uncover said aperture, and meansconnected with said operating means positioned to engage the notch of aphotographic plate within said chamber and to move said plate out ofalignment with said aperture upon movement of said operating means,whereby an additional plate may be introduced into said chamber.

IGOR B. BENSEN.

REFERENCES CITED The following references are of record in the file ofthis patent:

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